The invention relates to a travelling mechanism of a transport car for transporting files, and/or transport goods having similar dimensions or, respectively, similar weight, and running on horizontal and, in sections, vertical profile rail track and comprising a drive shaft coupled to an electric motor, said drive shaft carrying, in addition to a frictional drive wheel, a toothed drive wheel for rolling engagement with a toothed rack in the vertical profile rail tracks and having a pitch diameter dimensioned lower than the diameter of the frictional drive wheel.
In comparison to travelling mechanisms wherein the diameter of the frictional drive wheel and the pitch diameter of the toothed drive wheel are of at least approximately the same size, such a travelling mechanism exhibits the advantage of a better exploitation of the motor output because a higher travel speed can be achieved on the horizontal profile rail tracks than in the area of the vertical profile rail tracks. This advantage is achieved in a known electric transport rail system in that the frictional drive wheel is lifted off from its running rail in those areas of the profile rail track provided with a toothed rack. The toothed drive wheel thus runs in the toothed rack without play, this being necessarily connected with an increased wear of the toothed drive wheel and an increase in running noise.
This disadvantage is avoided in a transport rail system known from the German OS No. 25 45 907 having a transport car running on a rail in that the travelling mechanism of the transport car exhibits one or more auxiliary wheels mounted freely rotatable around its axle and in that auxiliary running surfaces are disposed at the rail in front of the area of toothed racks, the auxiliary wheels running up onto said auxiliary running surfaces and lifting the frictional drive wheel up from its running surface. This development of a transport rail system and of the transport car running on the transport rail system thus requires the application of an additional wheel to the travelling mechanism and of an additional running surface to a profile rail. This additional outlay and, in particular, the space requirement for the further wheel thereby induced is to be viewed as a serious disadvantage for the profile rails of conveyor systems for transporting files and/or transport goods having similar dimensions or, respectively, similar weight since as small as possible a space requirement for the profile rail tracks and the smallest possible dimensions and low weight of the travelling mechanism are a desired goal in such conveyor systems.